﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SubstringForStringBuilder
{
    static class SubstringForStringBuilder
    {
        static StringBuilder Substring(this StringBuilder str1,int index, int length) 
        {
            string str = str1.ToString();
            return  new StringBuilder(str.Substring(index,length));
        }
        static void Main(string[] args)
        {
            StringBuilder str = new StringBuilder();
            str.Append("manqshkooo");
            str = str.Substring(2, 4);
            Console.WriteLine(str.ToString());
        }
    }
}
